The present invention relates to a hydrostatic bearing of a rotating shaft, such bearings being utilized notably on machine tools, for boring or grinding spindles, for example.
There are three types of such bearings:
(a) simple hydrostatic bearings supplied with supporting fluid via fixed restrictions.
(b) "pressure-servoed" hydrostatic bearings, supplied via restrictions which vary as a function of the changes in pressure prevailing in the bearing support chambers.
(c) "position-servoed" hydrostatic bearings, supplied via restrictions which vary as a function of variations in position of the shaft with respect to a fixed reference, in a detection system tied to the bearing.
It is to the last type that the invention relates.
The aim of using such a technique is to obtain, when the shaft is subjected to a radial load, a minimal, if not zero, displacement of the former with respect to the bearing.
One can describe the rotating-shaft hydrostatic bearing of the type considered as comprising a support circuit including opposed support chambers around the said shaft receiving fluid under pressure and having a constant leakage with respect to the shaft, a radial position detection circuit for the shaft in the bearing including opposed detection chambers around the shaft receiving fluid under pressure and having a constant leakage with respect to the shaft, means of servoing the shaft in position activated by the detection circuit and acting on the support circuit, the said servoing means comprising a distributor with mobile element adapted to supply the opposed support chambers by the intermediary of constrictions varying in the inverse sense on one side or the other of its equilibrium position, the said mobile distributor element being integral in motion with a mobile corrector element subjected to the opposed actions of the fluid pressure prevailing in the opposed chambers of the detection circuit.
The known servoing means are not integrated in the bearing and involve the use of communicating passages which render the overall system complex and bulky.